Conventional authentication devices which execute an authentication processing based on a formation pattern of blood vessels inherent to a living body (which will be called a blood vessel formation pattern hereinafter) have been proposed.
This kind of authentication device picks up an image of a registrant by utilizing a characteristic that light within a near infrared band is peculiarly absorbed by deoxygenated hemoglobin (venous blood) or oxygenated hemoglobin (arterial blood). From a blood vessel image obtained as a result of the picking up of an image, a blood vessel formation pattern (hereinafter called a registered blood vessel formation pattern) is extracted and registered in a predetermined database.
The authentication device further extracts a blood vessel formation pattern of a target to authenticate (which will be called an authentication target's blood vessel formation pattern) like in the process of registration as described above, and compares this blood vessel formation pattern of the target sequentially with plural registered blood vessel formation patterns which have been registered in advance in a database. Thus, whether the target is an identical person (to the registrant) or not is determined (see, for example, Patent Document 1).
Patent Document 1: Japanese Patent Application No. 2003-242492
However, in this kind of authentication device, plural registered blood vessel formation patterns are sequentially compared until a registered blood vessel formation pattern corresponding to the authentication target's blood vessel formation pattern is found. Therefore, processing time required for comparison with the authentication target's blood vessel formation pattern tends to extend. This results in a problem that users have to wait for a longer time.
In particular, as the number of registered blood vessel formation pattern registered in the database increases, required processing time extends. This tendency results in that waiting time for users becomes much longer.